Squamous cell carcinoma of the conjunctiva (SCC) is a type of eye cancer that develops on the conjunctiva, the clear membrane covering the white part of the eyeball and lining the eyelids. Early detection and treatment are important for managing this condition, which focuses on removing cancerous cells and preventing recurrence.
What is Squamous Cell Carcinoma of the Conjunctiva?
Squamous cell carcinoma of the conjunctiva (SCC) is a type of cancer that develops from the epithelial cells, the outermost layer of cells, of this membrane. It is considered the most common malignancy of the conjunctiva in the United States, with an estimated yearly incidence of 1 to 2.8 cases per 100,000 people.
These cancerous growths typically exhibit slow progression, usually remaining confined to the eye’s surface. If left untreated, however, the tumor can locally invade deeper ocular structures, such as the cornea or sclera, and in rare instances, may spread to distant parts of the body through metastasis. SCC is part of a broader spectrum of eye diseases called ocular surface squamous neoplasia (OSSN), which ranges from precancerous lesions to invasive carcinoma.
Identifying Signs and Contributing Factors
Individuals with conjunctival SCC may notice several signs and symptoms. A persistent red eye, irritation, or a foreign body sensation are common initial complaints. A visible growth or lesion on the eye’s surface is also a frequent presentation, often appearing as a white, yellow-pink, or gelatinous nodule. These lesions can sometimes be fleshy or have a papillomatous (wart-like) or fibro-vascular appearance, often accompanied by dilated “feeder” blood vessels leading to the tumor. While vision may remain normal in early stages, changes like sensitivity to light, double vision, or decreased vision can occur as the disease progresses.
Several factors increase the likelihood of developing conjunctival SCC. Chronic exposure to ultraviolet (UV) radiation from sunlight is a primary risk factor, especially for individuals with outdoor occupations or those living closer to the equator. The link to UV-B radiation suggests DNA damage from sun exposure can lead to cancerous cells. Human papillomavirus (HPV) infection and immunosuppression, often seen in individuals with HIV/AIDS or those on organ transplant medications, also contribute to an elevated risk. Other contributing factors include fair skin, a tendency to sunburn, and older age, with the average age of affected patients around 56 years.
Diagnosis and Treatment Approaches
The diagnostic process for conjunctival SCC begins with a comprehensive eye examination, often utilizing a slit lamp to inspect the eye’s surface. While a clinical impression can suggest the tumor, a biopsy is the definitive method for diagnosis. This involves taking a small tissue sample (biopsy), which is then examined under a microscope to confirm the presence and type of cancerous cells.
Other imaging techniques may be employed to assess the lesion’s extent and determine if it has invaded deeper structures. Ocular Coherence Tomography (OCT) can help distinguish between benign and malignant cells. High-frequency ultrasound can also be used for larger lesions to determine if the tumor has extended into the eye or orbit.
Treatment options for conjunctival SCC are varied and often tailored to the tumor’s size, location, and invasiveness. Surgical excision, which involves removing the tumor with a margin of healthy tissue, is the primary treatment approach. During surgery, a margin of healthy tissue is removed. If the cornea is involved, a border of uninvolved corneal epithelium is also removed.
Adjunctive therapies are often used with surgery to reduce recurrence. Cryotherapy, a freezing technique, is applied to the margins of the surgical resection area to destroy any remaining cancer cells. Topical chemotherapy, using eye drops with medications like 5-fluorouracil (5-FU) or mitomycin C (MMC), can be administered for weeks to a year, especially for diffuse disease or as a post-operative therapy. Studies suggest topical 5-FU can significantly decrease recurrence risk. For more advanced or recurrent cases, radiation therapy, including external beam radiotherapy or brachytherapy (internal radiation), may be considered.
Recovery and Long-Term Outlook
Following treatment for conjunctival SCC, regular follow-up examinations are important to monitor for any signs of recurrence. Recurrence can occur from less than a month to several years after treatment. While recurrence is possible, the overall prognosis for conjunctival SCC is generally favorable, especially with early detection and appropriate treatment.
Ongoing vigilance is necessary, as SCC can recur even years after successful initial treatment. Patients are encouraged to adopt preventive measures to reduce the risk of future occurrences. This includes consistent sun protection, such as wearing UV-blocking sunglasses and wide-brimmed hats when outdoors. These actions can significantly lower the risk of developing SCC and other UV-related eye conditions.